Penetrance
by Swiss Army Knife
Summary: A timely visit from Uncle Sokka helps Bumi when he's feeling lost.


Author's Note: It's a great injustice that _The Legend of Korra_ didn't show Sokka's legacy in the form of his children, but at least we have Bumi. The focus on Korra's generation meant that there were only hints about Aang's family, but can you imagine being the oldest son of the Avatar, child of the South's greatest waterbending master, and yet have no bending ability of your own? Good thing Bumi has an uncle who knows something about being a "mere" man amidst forces of nature.

 **Penetrance**  
by Swiss Army Knife

Pen·e·trance – n. _the degree to which a genetic trait is expressed among those who carry it._

* * *

The roosterpigs had barely stopped crowing, and already it had been a long morning. Bumi wrinkled his nose; even after four months, he could still hardly believe such a small body could produce such a big stink. Taking care not to make a mess, he rolled up the soiled diaper and began wrapping his brother in a new one while Tenzen wiggled his wobbly arms and stretched his toes.

When it was done, Bumi gave his brother a look. "Now stay that way for five minutes, okay?"

"Stink-y baby," Kya singsonged from the table where she was busy pinching her oatmeal with her fingers.

Bumi shifted Tenzen into his arms. "Just eat your breakfast and shut up already, would you?"

Always the temperamental one, Kya's mood flared up like a fat, rainy thundercloud. "You don't get to tell me what to do."

Patience already thin, Bumi only just resisted an eye roll. Sometimes being the oldest was a pain, especially being _so much_ older. "Mama told you just this morning that I'm suppose to watch you while they get ready."

Kya thumped her messy hands on the table so that bits of her breakfast went flying everywhere, including onto her clean dress. "I'm not a baby like Tenzen. I don't need to get watched."

The baby in question made a gooey noise, and Bumi gave him a bounce in hopes of provoking a smile or a laugh. No luck, as usual. Just furrowed brows over serious grey eyes. Bumi sighed.

Kya, meanwhile, was sticking her tongue out at him. "You're _mean_ ," she accused.

"Well, you're obnoxious, you little pig, and Mama's going to be mad at you when she finds out you splattered your oatmeal."

Kya squalled, standing so abruptly that her bowl fell onto the floor. Then she reached for her cup and flung its contents in his direction. Usually, this would have ended with Bumi soaked and annoyed but otherwise fine. This time, however, was different. The water divided, catching the light with a white and gleaming edge. Bumi barely had time to turn his chin before shards of ice raked his ear and face. The pain shocked him so much he hardly understood what happened. Kya stood on her chair, the cup still in hand, her mouth hanging open. Then Tenzen burst into blustery tears.

That was the moment their mother came barging in, her unmade hair still flying around her face. "What happened?" she demanded.

Kya was the first to recover. "Bumi was bossing me," she railed, just as Bumi found his way past the numbness he felt and mumbled, "She threw ice at me."

Katara hurried over, lifting the red-faced Tenzen and looking the baby over anxiously. Tenzen wasn't hurt, and she gave a sigh of relief. A second later realization hit, and her eyes lit up. "Kya, you made ice?"

She stared at her daughter until both of them broke into wild smiles. "I did it!" Kya squealed. For months, Kya had been trying to master the next phase in her waterbending training – namely, the formation of ice. Katara went to her, lifting Kya onto her free hip and squeezing her in a fierce, elated hug.

"I can't wait to tell your father. He should be out here any minute now."

"My dress got messy," Kya complained.

"Then let's go change it." They were almost out of the room before Katara stopped. "Bumi, you should go change your shirt, too. You've got something on it."

Bumi stared at the empty door after they were gone, his mother and his siblings. Another drop of blood dripped off his chin and onto his stained collar. He wiped his cheek, forcing himself not to wince. It was just a few cuts. Except for some reason, despite the fact that the ice scraped his face, it was his chest that hurt most.

* * *

The party was in full swing. Every inch of the room was packed with important people from the four kingdoms, nibbling at spicy, vegetarian o'dourves and making small talk. Music from pipes and lyres played in the background, and all of the attention was focused on Tenzen, who was decked out in a little yellow outfit embroidered with saffron stitches. Air nomad colors to match his proud father, who held him in his arms.

Near the banquet table, Kya was once again perched on a chair in her pretty blue dress. Thrilled with her newly-found ability, she was soaking up the attention as she made people's drinks freeze over in their glasses. Katara stood by attentively.

Bumi stood alone against the back wall, trying not to sulk. He'd put a few plasters over the worst of the cuts on his cheek and neck. They stung, but not as bad as the feeling of standing by himself. This always happened when they had guests in the house, and there had certainly been enough of those in these last few months.

A woman wearing the latest Ba Sing Se fashion jostled him as she walked past with her husband. She paused to excuse herself. "Forgive me, young man. I didn't see you."

No one ever did. "Sorry," Bumi muttered, because he knew that was what he was supposed to say.

The adults shared a look. Probably they weren't very impressed by his manners. The man asked, "And what is your name?"

Bumi felt a surge of irritation. This was his house. Did he really need to be introduced? "I'm Bumi."

A flicker of interest passed over their faces. "Quite a name to live up do," the woman commented as she glanced at his tunic, which was an uninformative neutral color. She nodded, clearly drawing her own conclusions. It caused another angry surge to fill Bumi's belly, even though he knew it wasn't exactly fair. Unlike his siblings, nothing about him screamed his parentage. With his nondescript skin tone, Bumi could have come from anywhere. Even his pale eyes were incidental. There had been a lot of intermarriage, especially in this part of the world. "Are you here with your family?"

Bumi set his teeth together. "Yes."

"Then they'll appreciate this," the woman said, stretching out a finger toward an elegant vase made in classic Earth Kingdom style. Its lacquered sides gleamed in the gas lighting. A proud notch appeared between her eyebrows as she explained, "It's priceless; an heirloom, even." Her smile stretched. "A fitting gift for the son of the Avatar."

Bumi's hands turned into fists. "The Avatar has two sons, actually."

"Two? Well, yes, I suppose he does. Though it's hard to believe that even such powerful benders don't always breed true."

The man coughed discretely into his hand. "Meihui, please," he said. "Uncouth."

The woman hemmed. "Well, can you imagine? The last Air Nomad, and after so many –"

"Meihui," the man hissed again.

A tsking sound was her only response, but she did move on. "The girl, at least, has her mother's gifts, and now at last, this precious arrival!"

The words reminded Bumi of the day Tenzen was born. Finally allowed inside mother's room, Bumi had crowded close and let his new brother grip his finger. He'd been surprised by the strength of that little fist, and he'd looked up to share the moment. He'd found his mother tight-lipped, gazing beseechingly at his father. "This time?"

Aang wrapped her hand tenderly, kissing her knuckles. "I'm sure of it."

Bumi hadn't been sure what they meant, not until weeks later when Tenzen had given a tiny sneeze and all the books went flying off the shelves. Everyone froze, and then their mother burst into tears. After that there was a lot of noise and confusion. Father's element had come bursting out, rushing around all their cheeks with a smell of hay and grass. He'd gathered up Katara into his arms, and together they'd swung around and round.

"Finally," he'd said.

That night Bumi had laid in bed, thinking about what it meant. Tenzen was an airbender, that much was clear – the first one born for a hundred years. And Kya looked exactly like their mother and could already bend water. So what about Bumi?

Bumi tuned back into the conversation just as the man was wrapping his arm around his wife. "We're all proud," he said. "After all this time, a new age is finally dawning."

"A good age," his wife agreed.

They left without so much as a goodbye, wandering toward Bumi's family. Kya had run up beside Aang and tugged at his leg until he lifted her. Katara was holding Tenzen, a glow on her face. In his corner, Bumi wrapped his arms around himself. His heart began to pound until it grew painfully loud, until he could feel it against his temples.

Kya, so gifted.

Tenzen, so anticipated.

Mother, so happy.

Father, so proud.

Bumi knocked over the heirloom vase that had been brought all the way from Ba Sing Se, and watched it shatter into pieces with a huge noise.

* * *

"You broke that vase on purpose," Katara accused.

Bumi considered lying. An accident would earn him a scolding, sure, but it would save him from something worse. Unfortunately, he wasn't sure he could convince anyone. His streaming eyes and nose and his jutted, trembling lip didn't help. He looked toward the closed door, through which the sounds of the party could still be heard, and felt a thick knot in his throat. He barely knew now he felt. He just know that he couldn't stay in that room one more second.

Tearful, Bumi faced his mother and shouted, "I hate these parties. I feel invisible!"

It was a protest that he'd made before, and usually it was ignored, but apparently tonight had been too much. His mother's face turned dark and stormy. "Bumi, I'm tired this nonsense!"

"It's not nonsense. I can't stand it, Mama," Bumi tried to explain, hating the way his voice sounded high and thin, barely squeezing its way out of his throat. His fingernails were biting into his hands, but he couldn't bring himself to loosen his grip.

Katara splayed out her hands. "You can't stand what?"

The things he wanted to say stammered to a halt inside him, and he dropped his chin to his chest. Could he really say it out loud, in words? But – he looked, seeing his father right there, his mother, both of them rapt on him – was now finally the time they would hear him?

He decided to try. "Mama, when Tenzen was born, everything changed. It was bad enough with Kya, but now –"

"Stop. Just stop it right now, Bumi. I would have expected this kind of jealous behavior from Kya, but you're eleven-years-old. More than old enough to understand how much time and care a baby needs."

"It's not that," Bumi tried, already beginning to feel desperate. "I don't mind taking care of Tenzen. But what about us?" He looked at his dad. "I feel like I never even see you anymore –"

"Enough, Bumi. I don't want to hear another word. You should be ashamed of yourself. You make everyone upset when you talk like this."

Bumi's face, which already felt hot and tight, burned. "I don't mean to make you upset." Without thinking about what he was doing, his arms went up, reaching for her. "It's just –"

Katara stepped back and away. "I don't have time for these stupid games. I need you to act grown up _for once_ , and stop this babyish behavior."

Bumi looked toward his father, hoping for help, but all he saw was the man's long back as he left the room. The click of the door sliding shut was so loud that Bumi flinched.

His mother's lips were pressed tightly together. "Bumi, I want you to go to your room and stay there until the guests leave tonight."

Bumi stayed in one spot, his feet locked onto the floor, until his mother was gone. He rubbed his cheeks and nose with the backs of his hands, smearing away the evidence of his _babyishness_. Then he went to his room like he'd been told and listened to the distant sounds of clinking dishes and laughter until it all faded away.

* * *

That night, after the revelry was over and all the guests had gone home, a subdued Bumi helped his sister into her sleep shirt. As he tucked her into bed, she reached up and grabbed his face with both hands. She kissed his sore cheek.

"Sorry," she mumbled. "I didn't mean to."

Bumi leaned close enough to rub their noses together. "That's okay. I know."

She turned over and snuggled under the covers, satisfied that peace had been restored between them. However, as Bumi slipped into his own bed, he found that rest wasn't so easy for him. Outside the window the cold moon beat down, and he looked at her with uncertainty. The moon was supposed to be the origin of all waterbenders.

"Why didn't you make me one, too?" he whispered.

She did not answer. And, although Bumi listened restlessly for long minutes, hoping that his mother or – better still – his father might come in, that door also remained closed. Finally, restless and anxious, Bumi squirmed onto his side and listened to the skybisons lowing long into the night.

* * *

A few days had passed since the night of the broken vase, but things hadn't gone back to normal. Bumi didn't often see his father, who was still busy with intermittent visitors. The need to clear the air was strong, but whenever he opened his mouth to bring it up – at the dinner table, or in the common room at night – his mother shot him a warning look.

The strain was making it hard to sleep. If he did drift off, uneasy dreams woke him. By now he was so tired that his hands trembled, and that morning he had mostly just pushed his rice around, trying not to inhale for fear he might be sick.

His mother had brushed his forehead, frowning. "Are you feeling alright?" she'd asked, and Bumi's heart stuttered at the attention.

Then Tenzen kicked and knocked a bowl of porridge onto the ground. Katara swept the infant away, voice already soft with reassurance. Bumi had gone back to nudging his breakfast with a chopstick.

Now he leaned against the porch railing with his arms dangling, feeling sorry for himself. The day was almost gone, and the colors were deepening as they gathered in the west. A sound behind him drew his attention, and he wondered if Kya was getting into mischief. He went out into the hallway. "Kya?"

At first, he didn't recognize the silhouette he encountered, though the broad shoulders had a familiar cut. Then the man turned, and Bumi felt his mouth fall open.

In a voice that was far too small, he said, "Uncle Sokka?" and he shivered when that much-loved face arranged itself into a smile. The man opened his arms, and Bumi flew into them. At the same time, a dam broke somewhere inside, and everything – _everything_ – came tumbling loose.

"There, there," Uncle Sokka spoke. Careless words, but spoken with such warmth that Bumi felt his eyes grow even itchier and wetter. He'd missed this. The firm pressure against his neck from a hand that was nothing like the fluted, flittering fingers of his father. Now the man ended their embrace and took Bumi by the chin. "What's this?" he asked.

Bumi felt his face heat up. The shallow cuts had mostly scabbed over by now, but they'd gone untended and were still sore. "Kya made ice."

The man's jaw tightened.

"Sokka?" A feminine voice made both of them turn to where Katara was standing, her hands clasped together. "You arrived early!"

Sokka didn't say anything right away. On the color of her sea prunes or her hair loopies, he could and sometime did wax on for hours. However, at other times it seemed to Bumi that Sokka and his mother spoke some subtle, secret language, mostly with their eyes. Now there was a rebuke in the way Sokka gazed at her, and Bumi saw her face darken.

* * *

Things were strange at dinner, though an outsider would never have known. Uncle Sokka seemed like his usual self. He tossed bits of food into Kya's hair until she squalled and ran to him for a truly epic tickle fight. He joked with Aang. He even held Tenzen all through dessert, unperturbed when the baby drooled all over his tunic while chewing on one of its ivory toggles. Only when Tenzen's little fist reached for the carved blue stone he wore around his neck did he move to put it out of reach.

However, while on the surface everything seemed normal, there was no mistaking the underlying tension. It showed in how unusually quiet his mother was. She barely even flinched when Sokka took out his boomerang and started picking his teeth. Bumi looked between them uneasily, but then Sokka ruffled his hair with so much affection that Bumi's eyes got itchy again.

That night the children were sent to bed early. Bumi remained in their room only until he was sure that Kya was asleep, and then he slipped out into the hallway. He made his way until he could hear muffled voices. Stopping short of the narrow strip of light coming from his father's study, he listened.

Aang's voice was the first he heard. "I'm glad you made it here safely, Sokka. Was the passage a hard one?"

"Not too hard," Uncle Sokka answered. "The ice has mostly melted or migrated south."

"I still don't know why you didn't come in a steamer," Katara huffed, and Bumi could almost imagine the way she must be crossing her arms, like she always did when she felt someone was being ridiculous.

"Not this time. I wanted to have the cutter with me."

There was something significant about this response, some meaning that Bumi didn't understand, because suddenly everything went quiet. When Mother spoke, she sounded adamant. "No."

"Katara, things can't go on like this," Uncle Sokka said. "The last time I was here, I had to fish the kid out of the well, drag him out of trees. Tonight he barely said two words at dinner. Have you even spoken to him?"

"Of course we've spoken to him!"

Her angry shout was interrupted by Aang. "Actually, I think it's possible we've been avoiding the issue."

"Aang!"

"It's true," he said. "I just haven't known how to sit down and explain. It's complicated, the way I feel about Tenzen, especially right now. I'm not sure that I can put it into words he'll understand."

The was the sound of footsteps, and then a familiar creak as the basin where Tenzen slept was moved in its sling. It wasn't hard to imagine Katara standing over it, looking down at the squishy, infant face. "I love Bumi."

Bumi jerked, surprised to hear his own name. He leaned forward, risking detection so that he could just glimpse the three figures in the room. His mother stood by the cradle, while his father sat beside the sunken brazier with his hands clasped. Uncle Sokka's face was deeply creased as he frowned.

"I know that, Katara, but I'm not sure if either of you understand. You've always been what you are. Bending is the passion of your life."

Mother's back was turned. She held herself, and in a low, quiet voice, she asked, "Why did it have to be like this?"

Sokka stepped back, his expression hardening. "There's nothing wrong with that boy," he said sharply, "and if you aren't careful about letting stupid things like that slip out, you're going to ruin him. By action or inaction."

Katara turned, stricken.

"I saw his face," Sokka challenged.

The words had no apparent connection to what had come before, but Katara must have known what he meant, because she said, "It was nothing serious. Just a few scratches."

"So you did notice. I wondered."

"That's not fair. It was an accident. Kya doesn't have full control of her bending."

"Oh?" Uncle Sokka wondered. "Because I once knew a little girl who sometimes used her magic water to punish a mean older brother when she lost her temper."

"She made ice," Katara said. "We were excited."

"You've been excited about Tenzen, too, and there will be plenty more milestones for both of them. But what about Bumi?" A meaningful quiet filled up all the space in the room, leaving none left for an answer. Finally, Sokka said, "I've made up my mind."

The voices quieted down after that, the adults sitting together meditative silence, everything said which needed to be said. Bumi went back to his room and, despite how confused he felt, fell asleep.

* * *

Bumi woke up to someone shaking him. When he opened crusty eyelids, Uncle Sokka was leaning over him, a finger pressed to his lips. Wordless, he handed Bumi his shirt and boots, and – still half awake – Bumi struggled into them and followed his uncle out of the house. It was still very early, almost before dawn, and Bumi was puzzled as he was led onto the road. Only when he recognized it was the one leading to the docks did he understand. Uncle Sokka was leaving, and this was goodbye.

Without thinking, Bumi's hand shot out and grabbed his uncle's shirt.

Sokka chuckled. "What's with the manhandling? We haven't even left yet. Surely you're not pining already?"

Bumi's head jerked up. "Pining?" His heart started to race. "And what do you mean, ' _We'_?"

His uncle, who dearly loved a joke, seemed to be enjoying this one. His smile was like a catowl with cream. "Weeell, I thought the two of us might get out of here, take a little trip. What do you think?"

A trip, just him and Uncle Sokka. It would mean getting away from dressing nice, and being on his best behavior, and visitors who didn't know his name. From dirty diapers, and quarrels at breakfast. His mother's sharp looks, and his father's cold silences. If anything, Bumi could hardly contain himself. "When?"

Sokka gestured to the side of the road where two sacks were already sitting beside a basket of provisions. "How about now?"

* * *

Bumi had been in ships before, but mostly steamers powered by coal and fire. Huge vessels which carried trade and passengers all over the world. However, in his visits to the South Pole, he had seen the long, elegant cutters with their blue sails, each skillfully crafted by his mother's people. A few times, he'd been taken out on short trips into the bay, but only as a passenger, and never into the open ocean.

Now he had his first experience.

They exited the bay, leaving behind Air Island and the always-changing silhouette of Republic City. Soon there was nothing but a smear of dark green horizon and everything else was blue – waves and sky and sea. Uncle Sokka, at the tiller, laughed when a spray of foam broke against the side and soaked Bumi to the skin. The boy's startled face must have been something.

"Look over there," Sokka pointed to the west. "Go far enough in that direction and you'll hit the Fire Nation."

"Where Uncle Zuko lives," Bumi agreed. "I haven't seen him in awhile, but I think we're going to see him when Tenzen is bigger. Did you go visit before you came to Republic City?"

Uncle Sokka grimaced. "Yes, and he's as stubborn and moody as ever, although at least he has Mai and those brats to keep him from getting too sulky. Although one of them about took a notch out of my ear with a knife, and that jerk just stood there, _grinning_."

Bumi knew not to take the gripping too seriously. Whenever Uncle Zuko came, he talked about Sokka in the same way, calling him a peasant and – if the Water tribesman was present – occasionally setting him on fire. However, when Bumi asked about it, his dad said that they were actually best friends. That was just the way they acted.

He changed the subject. "One day I'd like to sail there myself."

"Do you like the ship?"

Bumi put his hand on the side of the boat and felt each small movement of the water beneath him. It was both terrifying and exhilarating. "It's smaller than I remember."

"This one is small," Sokka agreed. "It can be handled by only one or two men, if they know what they're doing."

Bumi stared at the vibrating lines and the taut sails, trying to understand the way they worked. "I wish I knew how."

A snort. "Well, what do you think we're here for? It's long past due for you to get a taste of sailing. It's your heritage, after all." Sokka pointed up at the tall wooden pole that held the sails. "This is the main mast, and the large sail is called the mainsail. The small triangular one forward is the jib, and _that_ is the staysail. The ship is propelled because they catch and direct the wind, while with the tiller," here he patted the beam beside which he sat, always holding on with one firm hand, "we're able to steer."

Bumi closed his eyes and leaned into the sharp wind. The smell of the sea was stronger than he'd ever experienced, and it made him feel good, strong. He wished he could stay out here forever.

When he turned his head, Uncle Sokka had an odd look on his face. Quiet and content. "You feel it, don't you?" he asked, and even though Bumi only half knew what he meant, he nodded back.

"I'm happy," he said, and he really was. For the first time in a long time, he felt like he could breathe.

Uncle Sokka gestured for him to come closer. "Lesson number one, then," he said, and so began the passage of a long, long day of learning every inch of the cutter with its sails and shrouds. Hard, exhausting work that left Bumi's heart singing with satisfaction. All of its overseen by his uncle, who spoke to him steadily through every trial and mistake, never losing his good humor, even when Bumi faltered.

* * *

Eventually a darker blue spread over the sky, and high above stars spread out like tiny chips of ice, cold and distant but so clear that Bumi felt like he could almost see each silver face winking. He turned to share this thought with Uncle Sokka, but found the man learning back against the stern of the boat, eyes fixed on the moon. His expression was hard to read, but to Bumi it seemed wistful.

"Uncle Sokka, are you alright?"

The man scrapped his fingers through his hair, sighing. "Nothing you need to worry about."

Bumi had his own complicated feelings about the moon, but he still couldn't help but wonder what that luminescent face might provoke in his uncle. "Does she make you sad?"

This time, instead of deflection, Sokka's eyes dimmed. "She reminds me of a long time ago. Someday I'll tell you about it, but for now I'd like to know why my favorite nephew's heart is breaking."

The words were so frank that Bumi's mind just stopped working for a second. "You can't call me that anymore," he managed eventually. "You have two nephews now."

Sokka tipped his head back. "I suppose you're right. Although, to be fair, Tenzen hasn't done much other than spit up all over my shirt." Jokes. He often used that joking tone, but Uncle Sokka was a Water tribesman. Beneath the surface, there were eddies and deep waters.

Bumi's shoulders slopped down. "Everyone else is pretty impressed with him."

Sokka shifted, considering. "You've had a lot of visitors come to see him, I guess."

"Sure," said Bumi. "Isn't that why you came?"

The boat shifted as Sokka leaned forward. He reached out and caught Bumi's chin, turning reluctant eyes until their gaze met. "Not a chance," he said. "I came for you."

Bumi's eyes burned. His sinuses had felt stuffy for days. "Really?"

Sokka laid back with a thump. "Absolutely. Babies are nothing but loud, sticky messes. You're much more interesting."

"But Tenzen can airbend," Bumi whispered. He looked up at the winking stars and found them blurrier than before. Fingers, warm and gentle, raked through the roots of Bumi's hair. He felt the tips against his scalp and closed his eyes.

Sokka said, "I expected we would talk like this one day."

"Since when?"

"Since Kya was born. She looked so much like Katara, you could already tell she would be a waterbender." He glanced sideways. "You were five and hadn't shown any sign, despite, well –"

"My dad being the Avatar." There was only a fragment of a second of hesitation, and then Sokka nodded. Bumi's chin sunk to his chest. "Were – were they disappointed when I was born?"

"Bumi, listen to me," Uncle Sokka said seriously. "You are no disappointment."

"But I can't bend. Not anything."

"Who gives a damn about bending?"

Bumi's mouth flew open at the ferocity in his uncle's voice, never mind the fact that he had just sworn right out loud.

"There are a lot of things a man can't do without," Sokka continued. "Compassion, character, a strong mind. But bending? Don't let me hear you think for one second that not being able to bend means you're missing something essential. It's just like having good balance or excellent eyesight or a head for navigation – it's a natural ability that takes training and practice to harness. You have plenty of abilities."

"If it's not important," Bumi wanted to know, "then why is everyone acting like it is? I love Tenzen, but everybody acts like he's more – more – "

"' _More'_?" Sokka prompted.

"More than me, I guess." And now that the confessions were rolling, it was as though Bumi couldn't keep them inside his mouth. "Dad doesn't meditate with me anymore. I wasn't very good at it, but he doesn't even ask. He doesn't read to me, or take me gliding. But when he's holding Tenzen his eyes get all soft. He's different. And the people. They keep coming, and they coo over my brother and they talk about how special he is. It's like I'm not even there." He was openly crying now. "It's not fair. I can't help it. I tried to bend, but I can't do it! Uncle Sokka, _why_?"

His uncle's expression was solemn, and he looked at his crying nephew with profound sorrow. His hand was over his own breast and the polished blue stone. The need to comfort was written on his face, but Bumi's cry for understanding was even stronger, and it was that which he ultimately chose to answer.

"Bumi," he said, "There are some things you need to know. Your father loves you, but Aang stands at the end of a long line of graves. All the Avatars. All his people. All your –"

He choked, as though his throat had suddenly closed, and Bumi felt it, too. He had been young, but he remember the teeny tiny boats that represented his lost family. The babies between him and Kya.

"We weren't sure Katara would have another baby other than you," Uncle Sokka continued, "and, once, Aang told me something I think you should hear. It was on one of those long nights afterward, and your mom had cried herself to sleep. I came out onto the porch where Aang was sitting. You were in his lap, so small that little ham fist of yours could still fit in your mouth. He said, 'We have Bumi. That's more than enough.'"

Bumi felt the tears welling again, persistent even though he scrubbed his eyes with both fists. "He said that?"

"He did," Uncle Sokka said. "I know that it may not always seem like it, but you are greatly treasured, Bumi. By me, by your parents, and by everyone else who really knows you. You're going to be a fine man."

The words slipped out before Bumi could restrain them. "Even without bending?"

"Come here," Sokka said, and made a space so that Bumi could squeeze in beside him in the stern of the boat. "Feel the tiller under your hand, the current alongside the ship. You're harnessing the water." He touched Bumi's hand to the taught, rattling sail. "Feel here. Do you sense that? We're harnessing the wind. And every time you strike flint together, fire is yours. Every time you build a dam, you move the earth." He reached into his boot and withdrew a long knife. "Even metal. Toph can shape it but not temper it. There are no limitations, Bumi. The world is yours, bending or no."

Bumi listened to the wind. "Dad can fly."

Sokka scoffed. "With a glider. But you can do that, too. After all, you're looking at the co-designer of the air balloon here. No airbender came up with that. Need inspires invention."

"What can I do, Uncle Sokka?"

A nose, pressed to his, so close Bumi could smell the man's breath. Sokka grinned with conviction. "Anything, Bumi. You can do anything."

A kind of peace was setting inside of Bumi, and with it, a flash of humor. He couldn't help it. "What about airbending?"

Uncle Sokka was good with humor. He met the twinkle in Bumi's eye, amplified it. Then he squeezed, bracing, reassuring. His eye caught the pale moon, which reflected like a silver disk on a pool of water. "Why not?" he asked. "Stranger things have happened."

* * *

Bumi woke up snoring into his uncle's armpit, which wasn't nearly as bad as one might think. Mostly the man smelled like brine: like sea and salt and foam. As he sat up and rubbed his eyes, Bumi could still hear the ocean, just down the strand of beach from where they'd made their camp. So far north, there wasn't much need for shelter from the elements, and in the end they'd simply pulled the boat beyond the high water mark and dug out a spot in the sand for a bed.

Which itched, Bumi reflected, casually bushing the gritty stuff from his arms and legs. But warm. Tucked in besides his uncle, he'd slept more deeply than he had in weeks. Though it might also have had to do with the tranquility of his mind after that long, glorious night of sailing. Not even dawn had roused him.

His gurgling stomach reminded him it was long past time for breakfast, and he shook his uncle's shoulder until the man groaned and turned over, blinking sleepily. "That time already? Well, okay."

They ate fish over a smoking fire, the dry wood licking with blue flames that made Bumi grin. He prodded his food with impatience until every one of his fingertips were burnt, but he didn't care. As they slowly ate, however, some of the old anxiety began trickling back.

Sokka saw it in his face and asked, "What are you thinking?"

"How do I go back?" Bumi wondered. He thought of all the times he'd tried to speak to his dad, and all the times that he failed. It made his throat click uncomfortably. "Everything is messed up, and I don't know how to fix it."

Sokka set aside the stick which had held his fish, now picked clean, and leaned forward. His chin rested on his hand, and he had the look of one who was considering deeply. Finally, he suggested, "You _could_ come back with me."

Bumi was stunned. "To the South Pole?"

"That's right. I have a lot of responsibilities, and I travel a lot, but between the work – well, let's just say I'd welcome having a family."

Bumi thought about it, trying to imagine himself in that vast place of ice and snow, amidst his mother and uncle's people. "I don't think I'd fit there," he said finally and held out his hands. Beside Sokka's, they were remarkably pale.

Sokka huffed in exasperation. He spread their hands together so they overlapped. "This," Sokka said, "doesn't mean anything. You're a Water tribesman, Bumi, and that's not skin deep. So what do you think? There are things I could teach you."

Things like sailing. Hunting. Even sword fighting if he wanted. However, it would also mean leaving home, and not just for a few days. Possibly it would be months before he saw his parents, Kya, Tenzen... As he thought about it, Bumi felt his sister's cool hands squished against his cheeks. Saw himself reflected in Tenzen's big grey eyes.

Eventually, his shoulders sagged. "I can't leave, Uncle Sokka," he said. "My brother and sister, they need me."

Before he knew what was happening, his uncle's long arms had him around the waist, dragging the gangly eleven-year-old from his spot in the sand into his arms. The embrace he gave was fierce, and despite the incongruous way Bumi was sprawled across his lap, Uncle Sokka said with conviction, "I'm proud of you. You're practically a man already."

A compliment like that would ordinarily have made Bumi swagger, but with his uncle it was different. Here, there was no need for pretence. Which was why, instead of shoving his uncle away, Bumi turned his face into his uncle's shoulder and held onto that embrace.

* * *

Author's Note: Just exploring some unanswered questions. Like, why is Bumi so much older than Tenzen? What happened to Suki, and why didn't we meet any of Sokka's children? Also, Bumi's position is really interesting. He's the oldest in his family, whereas both his parents were "younger" (Katara literally and Aang within the dynamics of the gaang). From personal experience, I can testify that this does color interactions with even the most well-meaning parents, who often sympathize with the littler ones. He's also a non-bender amongst all benders, and that can't have been easy. Fortunately, he has his Uncle Sokka. I want them to have lots of adventures together. We can at least imagine it, right?

 **Please leave me a comment if you can.** My favorites are when you point out a line or moment that stood out to you. Thank you so much; you're wonderful!


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